Laser scanning system employing an optics module capable of forming a laser beam having an extended depth of focus (dof) over the laser scanning field

ABSTRACT

A laser scanning system having a laser scanning field, and a laser beam optics module with an optical axis and including: an aperture stop disposed after a laser source for shaping the laser beam to a predetermined beam diameter; a collimating lens for collimating the laser beam produced from the aperture stop; an apodization element having a first and second optical surfaces for extending the depth of focus of the laser beam from the collimating lens; and a negative bi-prism, disposed after the apodization element, along the optical axis, to transform the energy distribution of the laser beam and cause the laser beam to converge to substantially a single beam spot along the far-field portion of the laser scanning field, and extend the depth of focus of the laser beam along the far-field portion of the laser scanning field.

BACKGROUND

1. Field of Disclosure

The present disclosure relates to an improved method of and apparatusfor extending the depth of focus (DOF) of a laser beam used in a laserscanning bar code symbol reading system, and more particularly,extending the depth of focus of the laser scanning beam over both thefar-field and near-field portions of the laser scanning field.

2. Brief Overview of the State of The Art

The use of laser scanning bar code symbol reading systems is well knownin the art. As shown in FIG. 1, conventional laser scanning systems havethe capacity to scan and read bar code symbols 116 over the laserscanning field 115 using a laser scanning beam 10 generated from aconventional visible laser diode (VLD), an aperture stop, and acollimating lens.

As shown in FIG. 2 attempts to improve the depth of focus ofconventional laser scanning systems have proposed the use of aperturestops and axicon lens combinations, after the light collimating lens, tofocus the laser beam and minimize beam spread during the propagation ofthe laser beam 10 during scanning operations within the working range ofthe system.

U.S. Pat. No. 5,080,456 to Katz et al and U.S. Pat. No. 5,331,143 toMarom et al disclose the use of axicon (i.e. rotationally-symmetric)optical elements for shaping laser beams, and extending the depth offocus thereof in laser scanning systems.

While axicon elements help to extend the depth of focus of laser beams,the resulting laser beams typically have limitations when scanning fine(i.e. 3 mil) code symbols at short ranges, while allowing reading ofcoarse (i.e. 100 mil) code symbols at long ranges (greater then 100inches from the light transmission window).

Thus, there is a great need in the art to provide an improved method ofand apparatus for generating laser beams having an extended depth offocus, without the shortcoming and drawbacks of prior art systems which,hitherto, have compromised system performance in significant ways.

OBJECTS OF PRESENT DISCLOSURE

A primary object of the present disclosure is to provide an improvedmethod of and apparatus for generating a laser beam capable of scanninghigh-density (e.g. 3 mil) bar code symbols at short-range distances(e.g. less than 6.0 inches from the light transmission window) and lowdensity bar codes (100 mil) at long range distances from the system.

Another object is to provide a laser scanning bar code symbol readingsystem for having the capacity to laser scan and read high-density barcode symbols at both short range distances (e.g. less then 6 inches) andlong range distances (e.g. greater than 100 inches) from the from thelight transmission window of the scanning system.

Another object of the present invention is to provide such a laserscanning bar code symbol reading system, with a laser beam optics modulehaving an aperture stop, a light collimating lens, an apodizationoptical lens element, and a negative bi-prism, arranged together as anoptical assembly, causing the energy distribution of the laser beamproduced therefrom to converge substantially to a single spot atpredetermined far-field distance (e.g. 100 inches) from the lighttransmission window of the scanning system.

Another object of the present invention is to provide an improved opticsmodule for producing a laser beam, wherein the optics module comprisesan assembly of components including an aperture stop, a lightcollimating lens, an apodization optical lens element, and a negativebi-prism, arranged together to causing the energy distribution of thelaser beam produced therefrom to converge to a single spot atpredetermined far-field distance (e.g. 100 inches) from the lighttransmission window of the scanning system.

Further objects of the present disclosure will become more apparentlyunderstood hereinafter and in the Claims appended hereto.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more fully understand the Objects, the following DetailedDescription of the Illustrative Embodiments should be read inconjunction with the accompanying Drawings, wherein:

FIG. 1 is a perspective view of an illustrative embodiment of aconventional laser scanning bar code symbol reading system, having thecapacity to scan and read bar code symbols in its scanning field using alaser scanning beam generated from a conventional laser beam productionmodule comprising a laser diode, a collimating lens, and an axicon (i.e.rotationally-symmetric prism lens), specified in FIG. 2;

FIG. 2 is a schematic representation of the conventional laser beamproduction module employed in laser scanning bar code symbol readingsystem illustrated of FIG. 1, comprising a laser scanning beam generatedusing a laser diode, a collimating lens, and axicon (i.e.rotationally-symmetric prism lens), as shown;

FIG. 3 is a perspective view of an illustrative embodiment of ahand-supportable laser scanning bar code symbol reading system accordingto the present disclosure, having the capacity to scan and read bar codesymbols in its scanning field using an improved laser scanning beamgenerated a laser beam production module comprising a laser diode, acollimating lens, an apodization element, and a negative bi-prismoperably connected thereto along the optical axis of the apodizingelement;

FIG. 4 is a schematic block diagram describing the major systemcomponents of the laser scanning bar code symbol reading system shown inFIG. 3;

FIG. 5A is a 3D optical schematic diagram of the improved laser beamoptics module employed in the laser scanning bar code symbol reader ofFIG. 3, and shown comprising a collimating lens, an apodization elementand a negative bi-prism element, arranged together as an optical lensassembly;

FIG. 5B is a 2D optical schematic diagram of the improved laser beamoptics module (i.e. assembly) shown in FIG. 5A;

FIG. 6A is a first 3D perspective view of the apodization lens elementemployed in the laser beam optics assembly depicted in FIGS. 5A and 5B;

FIG. 6B is a second 3D perspective view of the apodization lens elementemployed in the laser beam optics assembly depicted in FIGS. 5A and 5B;

FIG. 7A is a graphical representation specifying the front surfaceprofile of the apodization element employed in the laser beam opticsmodule shown in FIGS. 5A and 5B;

FIG. 7B is a graphical representation specifying the rear surfaceprofile of the apodization element employed in the laser beam opticsmodule shown in FIGS. 5A and 5B;

FIG. 8 is a 3D perspective view of the negative bi-prism lens elementemployed in the laser beam optics assembly depicted in FIGS. 5A and 5B;

FIG. 9 is a graphical representation specifying the x and y profile ofthe negative bi-prism employed in the improved laser beam optics moduleshown in FIGS. 5A and 5B;

FIG. 10 is a schematic representation illustrating variation in thecross-sectional dimensions and characteristics of laser beam producedfrom the improved laser beam optics module shown in FIGS. 5A and 5B, atseveral discrete distances (e.g. 6″, 36″, and 300″ from the exit pupilof the optics assembly);

FIG. 11A is a plot of the point spread function (PSF) of the laser beamat 6 inches from the exit of the negative bi-prism employed in the laserbeam optics module shown in FIGS. 5A and 5B, showing slight convergenceof the spatially-distributed energy distribution of the laser at thisscanning distance;

FIG. 11B is a plot of the point spread function of the laser beam at 36inches from the exit of the negative bi-prism employed in the laser beamoptics module shown in FIGS. 5A and 5B, showing significant convergenceof the energy distribution of the laser beam into two closely-spacedpoints at this scanning distance;

FIG. 11C is a plot of the point spread function of the laser beam at 300inches from the exit of the negative bi-prism employed in the laser beamoptics module shown in FIGS. 5A and 5B, showing the convergence of theenergy distribution of the laser beam into a single point (i.e. narrowbeam waist) at this scanning distance; and

FIGS. 12A and 12B, taken together, set forth a flow chart describing theprimary steps carried out when controlling the laser scanning system ofFIG. 3 during it manually-triggered mode of operation.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

Referring to the figures in the accompanying Drawings, the illustrativeembodiments of the laser-scanning bar code symbol reading system will bedescribed in great detail, wherein like elements will be indicated usinglike reference numerals.

As shown in FIG. 3, the laser scanning bar code symbol reading system100 comprises: a hand-supportable housing 102 having a head portion anda handle portion supporting the head portion; a light transmissionwindow 103 integrated with the head portion of the housing 102; amanually-actuated trigger switch 104 integrated with the handle portionof the housing, for activating its laser scanning module 105 with alaser scanning field 115; and an IR-based object detection subsystem 219generating an IR beam within the near-field portion of the laserscanning field, as shown in FIG. 3, for automatically detecting thepresence of an object in the near field portion of the laser scanningfield, and triggering the system when an object is automaticallydetected in near portion of the scanning field.

As shown in FIGS. 3 and 4, the laser scanning bar code symbol readingsystem 100 further comprises: a laser scanning module 105, forrepeatedly scanning, across the laser scanning field, either (i) a laserbeam generated by a near-field laser source 112A (e.g. VLD and/or IR LD)having optics to produce a laser scanning beam focused in the nearportion of the laser scanning field, in response to a first controlsignal generated by a system controller 150 when the module 105 isoperating in its near-field laser illumination mode of operation, or(ii) a laser beam generated by a far-field laser source 112B (e.g. VLDand/or IR LD) having optics 200 to produce a laser scanning beam havingan extended depth of focus (DOF) within the far portion of the laserscanning field, in response to a second control signal generated by thesystem controller 150 when the module 105 is operating in its far-fieldlaser illumination mode of operation, wherein the mode of operationdepends on the results of real-time analysis performed by the systemcontroller 150 while carrying out the method of operation, specified inFIG. 3; wherein the laser scanning module 105 also includes a laserdrive circuit 151 for receiving first and second control signals fromsystem controller 150, and in response thereto, generating anddelivering first and second laser (diode) drive current signals to thenear-field laser source 112A and the fair-field laser diode source 112B,respectively, to selectively produce near-field and far-field laserscanning beams during the method of bar code symbol reading described inFIG. 3; light collection optics 106 for collecting lightreflected/scattered from scanned object in the scanning field, and aphoto-detector for detecting the intensity of collected light andgenerating an analog scan data signal corresponding to said detectedlight intensity during scanning operations; an analog scan data signalprocessor/digitizer 107 for processing the analog scan data signals andconverting the processed analog scan data signals into digital scan datasignals, which are then converted into digital words representative ofthe relative width of the bars and spaces in the scanned code symbolstructure; programmed decode processor 108 for decode processingdigitized data signals, and generating symbol character datarepresentative of each bar code symbol scanned by either a visible orinvisible laser scanning beam; an input/output (I/O) communicationinterface module 140 for interfacing with a host communication systemand transmitting symbol character data thereto via wired or wirelesscommunication links that are supported by the symbol reader and hostsystem; and a system controller 150 for generating the necessary controlsignals for controlling operations within the hand-supportable laserscanning bar code symbol reading system.

In general, system 100 has a manually-triggered mode of system operationcontrolled using trigger switch 104, as specified in FIGS. 12A and 12B.Also, system 100 also an automatically-triggered mode of systemoperation controlled using IR-based object detection subsystem 219.

As shown in FIGS. 5A and 5B, laser beam optics module 200 for thefar-field range laser beam provides a simple and effective solution tospot separation issue of conventional optics module design.

As shown in FIGS. 5A and 5B, laser beam optics module 200 comprises: anaperture stop 201 (disposed after VLD 112B, or a negative bi-prism 204,or at an intermediate location) for shaping the beam to a diameter 2R; acollimating lens 202 for collimating the input laser beam from theaperture stop; an apodization (i.e. rotationally symmetric) element 203having a first and second optical surfaces as specified in FIGS. 7A and7B for extending the depth of focus of the output laser beam; and anegative bi-prism 204, disposed immediately after the apodizationelement 203, along its optical axis, to transform the energydistribution of the laser beam can cause the laser beam to converge to asingle beam spot at long distances (e.g. 100 inches) from the scanningwindow, and scan low-density bar code symbols over the far (i.e. longdistance) scanning range and high density bar code over the near (i.e.short) distance scanning range.

The primary function of the negative bi-prism element 204 is to reducebeam spot separation over the far-field ranges, as clearly shown in FIG.11C. Spot separation trade off between near and far range can beadjusted by changing the bi-prism angle α between the planes of thenegative bi-prism 204, shown in FIG. 8.

In the illustrative embodiment, the bi-prism angle α is selected to beabout 0.5 degrees which causes the laser beam to converge into a singlebeam spot at the 100″ range (i.e. over the far field), and the laserbeam to degenerate into two beam spots separated by to ˜1.5 mm at the 6″range (i.e. over the near field).

Preferably, IR-based object detection subsystem 219 is mounted in thefront of its light transmission window 103 so that the IR lighttransmitter and IR light receiver components of subsystem 219 have anunobstructed view of an object within the laser scanning field of thesystem, as shown in FIG. 1. Also, the IR object presence detectionmodule 219 can transmit into the scanning field 115, IR signals having acontinuous low-intensity output level, or having a pulsedhigher-intensity output level, which may be used under some conditionsto increase the object detection range of the system. In alternativeembodiments, the IR light transmitter and IR light receiver componentscan be realized as visible light (e.g. red light) transmitter andvisible light (e.g. red light) receiver components, respectively, wellknown in the art. Typically the object detecting light beam will bemodulated and synchronously detected, as taught in U.S. Pat. No.5,340,971, incorporated herein by reference.

As shown in FIG. 4, the laser scanning module 105 comprises a number ofsubcomponents, namely: laser scanning assembly 110 with anelectromagnetic coil 128 and rotatable scanning element (e.g. mirror)134 supporting a lightweight reflective element (e.g. mirror) 134A; acoil drive circuit 111 for generating an electrical drive signal todrive the electromagnetic coil 128 in the laser scanning assembly 110;and near-field laser beam source 112A for producing a near-field visiblelaser beam 113A, and far-field laser beam source 112B and optics module200 for producing a far-field visible laser beam 113B; and a beamdeflecting mirror 114 for deflecting the laser beam 113A, or 113B(depending on which laser source is enabled at any instant in time bysystem controller 150) as incident beam 114A towards the mirrorcomponent of the laser scanning assembly 110, which sweeps the deflectedlaser beam 114B across the laser scanning field and a bar code symbol 16that might be simultaneously present therein during system operation.

As shown in FIG. 4, the laser scanning module 105 is typically mountedon an optical bench, printed circuit (PC) board or other surface wherethe laser scanning assembly is also, and includes a coil support portion110 for supporting the electromagnetic coil 128 (in the vicinity of thepermanent magnet 135) and which is driven by a drive circuit 111 so thatit generates magnetic forces on opposite poles of the permanent magnet135, during scanning assembly operation.

In general, system 100 supports a manually-triggered triggered mode ofoperation, and the bar code symbol reading method described below.

In response to a triggering event (i.e. manually pulling trigger 104),the laser scanning module 105 generates and projects a laser scanningbeam through the light transmission window 103, and across the laserscanning field external to the hand-supportable housing, for scanning anobject in the scanning field. The laser scanning beam is generated byeither the near-field laser beam source 112A or the far-field laser beamsource 112B, in response control signals generated by the systemcontroller 150. The scanning element (i.e. mechanism) 134 repeatedlyscans the selected laser beam across a code symbol residing on an objectin the near portion or far portion of the laser scanning field 115.Then, the light collection optics 106 collects light reflected/scatteredfrom scanned code symbols on the object in the scanning field, and thephoto-detector (106) automatically detects the intensity of collectedlight (i.e. photonic energy) and generates an analog scan data signalcorresponding to the light intensity detected during scanningoperations. The analog scan data signal processor/digitizer 107processes the analog scan data signals and converts the processed analogscan data signals into digitized data signals. The programmed decodeprocessor 108 decode processes digitized data signals, and generatessymbol character data representative of each bar code symbol scanned byeither a near-field or far-field laser scanning beam. Symbol characterdata corresponding to the bar codes read by the decoder 108, are thentransmitted to the host system via the I/O communication interface 140which may support either a wired and/or wireless communication link,well known in the art. During object detection and laser scanningoperations, the system controller 150 generates the necessary controlsignals for controlling operations within the hand-supportable laserscanning bar code symbol reading system.

Referring to FIGS. 12A and 12B, the method of reading bar code symbolsand controlling operations within the laser scanning bar code reader 100will be described in greater detail.

As indicated in FIG. 12A, the process orchestrated by system controller150 begins at the START Block. Then at Block A1 in FIG. 12A, the systemcontroller determines if a trigger event has occurred (i.e. whether ornot trigger 104 has been manually depressed by the operator upon seeingan object in the laser scanning field and pointing the head portion ofthe housing towards the object). In the event that a trigger event hasbeen detected at Block A1, then the system is activated and the systemcontroller determines at Block A2 whether or not the IR object presencedetection subsystem 219 detects the object in the near portion of thelaser scanning field 115. If IR object presence detection subsystem 219detects an object in the near portion of the scanning field 115, then atBlock B, the system controller 150 directs the laser scanning module 105to scan the detected object with a laser beam generated by thenear-field VLD 112A.

At Block C in FIG. 12A, the decode processor 108 runs a decode algorithmon the captured scan data, and if at Block D, a bar code symbol isdecoded, then at Block E, the produced symbol character data istransmitted to the host system, and the system controller returns toBlock A1. If, however, at Block D a bar code symbol is not decoded, thenthe system controller 150 determines at Block F1 whether or not themaximum scan attempt threshold has been reached, and if not, then thesystem controller 150 returns to Block B, and resumes the flow asindicated. However, if at Block F1, the system controller 150 determinesthat the maximum scan attempt threshold has been accomplished, then thesystem controller 150 proceeds to Block F2 and sends a Failure to Decodenotification to the operator and returns to Block A1.

If at Block A2 an object is not detected in the near portion of thelaser scanning field, then at Block G in FIG. 12B, the system controllerdirects the laser scanning module 105 to scan the detected object with alaser beam generated by the far-field VLD 112B and optical module 200.Then at Block H, one or more decode algorithms are run on the collectedscan data, and at Block I, the system controller 150 determines whetheror not a bar code symbol is decoded by the decode processor 108. If, atBlock I, a bar code symbol is decoded, then at Block J the producedsymbol character data is transmitted to the host system, and systemcontrol returns to Block A1, as shown in FIG. 3. If, however, at BlockI, no bar code symbol is decoded, then the system controller 150determines whether or not the maximum scan attempt threshold (i.e. howmany attempts to decode are permitted) has been reached, and so long asthe maximum number has not been reach, the system controller 150maintains a control loop between Blocks K and G, as indicated in FIG.12B. When the maximum number of attempts to decode has been reached atBlock K, then system controller 150, optionally, sends a Failure toDecode notification to the operator, and the system returns to Block A1,as shown in FIG. 12A.

The above method of reading bar code symbols and controlling systemoperations is carried out in an automated manner within the laserscanning bar code symbol reader 100, wholly transparent to the operatorwho is holding the system in his or her hand.

By virtue of this unique method of control, the system is capable ofreading both bar code symbols in near and far field portions of thelaser scanning field, in a user-transparent manner using laser sourceswitching during laser scan data capture and processing operations,without the complexities presented by prior art techniques andtechnologies.

The above method of reading bar code symbols and controlling systemoperations can also be carried out in an automated manner using anIR-based long-short range object detection and presence detectionsubsystem, capable of automatically determining whether or not andetected object is located within the near-field or far-field range ofthe system, and in response therefrom the system controller 150automatically generating control signals to activate or drive thenear-field or far-field laser beam production module, as the case maybe, in wholly transparent to the operator who may be holding the systemin his or her hand, or the system is supported in a stand on acountertop surface. By virtue of this alternative method of control, thesystem is capable of reading both bar code symbols in near and far fieldportions of the laser scanning field, in a user-transparent manner usinglaser source switching during laser scan data capture and processingoperations, without the complexities presented by prior art techniquesand technologies.

Some Modifications which Readily Come to Mind

While the illustrative embodiments disclosed the use of a 1D laserscanning module to detect scan visible and/or invisible bar code symbolson objects, it is understood that a 2D or raster-type laser scanningmodule can be used as well, to scan 1D bar code symbols, 2D stackedlinear bar code symbols, and 2D matrix code symbols, and generate scandata signals for decoding processing.

While hand-supportable dual laser scanning systems have beenillustrated, it is understood that the laser scanning systems can bepackaged in modular compact housings and mounted in fixed applicationenvironments, such as on counter-top surfaces, on wall surfaces, and ontransportable machines such as forklifts, where there is a need to scancode symbols on objects (e.g. boxes) that might be located anywherewithin a large scanning range (e.g. up to 20+ feet away from thescanning system). In such fixed mounted applications, the trigger signalcan be generated by manual switches located a remote locations (e.g.within the forklift cab near the driver) or anywhere not located on thehousing of the system.

Also, the illustrative embodiment have been described in connection withvarious types of code symbol reading applications involving 1-D and 2-Dbar code structures (e.g. 1D bar code symbols, 2D stacked linear barcode symbols, and 2D matrix code symbols), it is understood that thepresent invention can be used to read (i.e. recognize) anymachine-readable indicia, dataform, or graphically-encoded form ofintelligence, including, but not limited to bar code symbol structures,alphanumeric character recognition strings, handwriting, and diversedataforms currently known in the art or to be developed in the future.Hereinafter, the term “code symbol” shall be deemed to include all suchinformation carrying structures and other forms of graphically-encodedintelligence.

It is understood that the digital-imaging based bar code symbol readingsystem of the illustrative embodiments may be modified in a variety ofways which will become readily apparent to those skilled in the art ofhaving the benefit of the novel teachings disclosed herein. All suchmodifications and variations of the illustrative embodiments thereofshall be deemed to be within the scope of the Claims appended hereto.

What is claimed is:
 1. A laser scanning code symbol reading system forreading code symbols comprising: a housing with a light transmissionwindow; a laser scanning module, disposed in said housing, for scanninga laser beam across a laser scanning field having a near portion and afar portion defined external to said light transmission window, whereinsaid laser scanning module is responsive to one or more control signalsgenerated by a system controller and includes (i) a laser drive modulefor driving a far-field laser source and a far-field laser beam opticsmodule to produce a far-field laser beam in response to receiving saidone or more control signals from said system controller, and (ii) alaser scanning mechanism for scanning said far-field laser beam acrosssaid laser scanning field and a code symbol on an object in said laserscanning field; wherein said far field laser beam optics module havingan optical axis and including: an aperture stop for shaping the beam toa predetermined diameter; a collimating lens for collimating said laserbeam produced from said aperture stop; an apodization element having afirst and second optical surfaces for extending the depth of focus ofsaid laser beam from said collimating lens; and a negative bi-prism,disposed immediately after said apodization element, along said opticalaxis, to transform the energy distribution of said laser beam and causethe laser beam to converge to substantially a single beam spot alongsaid far-field portion of said laser scanning field, so as to extend thedepth of focus of said laser beam along said far-field portion of saidlaser scanning field; light collection optics, disposed in said housing,for collecting light reflected/scattered from scanned object in saidlaser scanning field; a photo-detector, disposed in said housing, fordetecting the intensity of collected light from said code symbols, andgenerating an analog scan data signal corresponding to said detectedlight intensity during laser scanning operations; an analog scan datasignal processor, disposed in said housing, for processing said analogscan data signals and converting the processed analog scan data signalsinto digitized data signals; a programmed decode processor, disposed insaid housing, for decode processing said digitized data signals, andgenerating symbol character data representative of each code symbolscanned by said far-field laser beam; and an input/output (I/O)communication interface, disposed in said housing, for interfacing witha host system and transmitting symbol character data to said hostsystem, via a communication link, supported by said laser scanning codesymbol reading system and said host system; said system controller forcontrolling operations within said laser scanning bar code symbolreading system.
 2. The laser scanning code symbol reading system ofclaim 1, wherein said housing comprises a hand-supportable housing. 3.The laser scanning code symbol reading system of claim 1, wherein saidcode symbols are symbols selected from the group consisting of 1D barcode symbols, 2D stacked linear bar code symbols and 2D matrix codesymbols.
 4. The laser scanning code symbol system of claim 1, whereinsaid communication link is either a wired or wireless communicationlink.
 5. A laser scanning bar code symbol reading system, comprising: ahousing having a light transmission window, and a laser scanning fieldhaving near and far field portions defined external to said lighttransmission window; a laser source for producing a laser beam; a laserbeam optics module for transforming said laser beam into a laser beamhaving an extended depth of focus over said far portion of said laserscanning field; and wherein said laser beam optics module having anoptical axis and including: an aperture stop for shaping said laser beamto a predetermined beam diameter; a collimating lens for collimatingsaid laser beam produced from said aperture stop; an apodization elementhaving a first and second optical surfaces for extending the depth offocus of said laser beam from said collimating lens; and a negativebi-prism, disposed after said apodization element, along said opticalaxis, to transform the energy distribution of said laser beam and causethe laser beam to converge to substantially a single beam spot alongsaid far-field portion of said laser scanning field, and extend thedepth of focus of said laser beam along said far-field portion of saidlaser scanning field; and a laser scanning mechanism for scanning saidlaser beam across the far-field portion of said laser scanning field anda code symbol on an object in said far-field portion of said laserscanning field;
 6. The laser scanning system of claim 5, which furthercomprises: light collection optics, disposed in said housing, forcollecting light reflected/scattered from scanned object in saidfar-field portion of said laser scanning field; a photo-detector,disposed in said housing, for detecting the intensity of collected lightfrom said code symbols, and generating an analog scan data signalcorresponding to said detected light intensity during laser scanningoperations; an analog scan data signal processor, disposed in saidhousing, for processing said analog scan data signals and converting theprocessed analog scan data signals into digitized data signals; aprogrammed decode processor, disposed in said housing, for decodeprocessing said digitized data signals, and generating symbol characterdata representative of each code symbol scanned by said laser beam; andan input/output (I/O) communication interface, disposed in said housing,for interfacing with a host system and transmitting symbol characterdata to said host system, via a communication link, supported by saidlaser scanning system and said host system; said system controller forcontrolling operations within said laser scanning system.
 7. The laserscanning system of claim 5, wherein said housing comprises ahand-supportable housing.
 8. The laser scanning system of claim 6,wherein said code symbols are symbols selected from the group consistingof 1D bar code symbols, 2D stacked linear bar code symbols and 2D matrixcode symbols.
 9. A laser beam optics module for transforming a laserbeam produced from a laser beam source, into a laser beam having anextended depth of focus over a far portion of a laser scanning field,wherein said laser beam optics module has an optical axis and comprises:an aperture stop for shaping said laser beam to a predetermined beamdiameter; a collimating lens for collimating said laser beam producedfrom said aperture stop; an apodization element having a first andsecond optical surfaces for extending the depth of focus of said laserbeam from said collimating lens; and a negative bi-prism, disposed aftersaid apodization element, along said optical axis, to transform theenergy distribution of said laser beam and cause the laser beam toconverge to substantially a single beam spot along said far-fieldportion of said laser scanning field, and extend the depth of focus ofsaid laser beam along said far-field portion of said laser scanningfield.